Micro-Electro-Mechanical Systems (MEMS) refer to the integration of mechanical elements and electronics on a semiconductor substrate through microfabrication technology. While the electronics are fabricated using integrated circuit (IC) processes, the micromechanical elements are fabricated using compatible “micromachining” processes that selectively etch away parts of the silicon wafer to form the mechanical and electromechanical devices.
MEMS have been fabricated using modified versions of the same semiconductor fabrication technology used to make electronics (e.g., CMOS). These include: molding and plating, wet etching (potassium hydroxide (KOH), or Tetra-Methyl Ammonium Hydroxide (TMAH)) and dry etching (reactive ion etching (RIE) and deep reactive ion etching (DRIE)), electro discharge machining (EDM), and other technologies capable of manufacturing very small devices.
For some MEMS devices, the material used for conventional fabrication processes can be plasma etched, but has poor mechanical properties and a short lifetime. It would be desirable to use a material with good mechanical properties and corrosion resistance, to improve the MEMS life time. However, if the material that is selected for fabricating the MEMS is corrosion resistant, the material would also be resistant to dry etching by typical plasma, or wet etching by a wet bench process.
Improved MEMS fabrication techniques are desired.